Their first piece of advice is not to leave your car running unattended.

It is bad for the environment, and tempting to would-be thieves - but it can also be illegal.

A spokesman said: "On cold and frosty mornings, it's tempting to start up the car and head back inside, letting it running with the heater and demister on, waiting for the windows to defrost.

"But did you know that doing so could potentially land you in hot water?"

Leaving the engine running on a vehicle parked on the public road is an offence under regulations 98 and 107 of the Road Vehicles (Construction and Use) Regulations 1986, which reinforces rule 123 of the Highway Code.